"People don't know this, but I got nervous," he revealed to TV Line. "I was really nervous. To jump back into that role and start quoting Sun Tzu, and I'm looking at Tom [Welling]? It felt so surreal. I was going, 'Can I do this?' And finally you just do it!"

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He also claimed that returning to Smallville to shoot the final scenes was an "amazing" experience.

"There were people who worked on that crew that aren't even working on the show anymore that came to see me," he said. "It was like a family I hadn't seen in a while."

Rosenbaum also joked about the bald cap that he was forced to wear for the episode, due to his new role in Fox sitcom Breaking In.

"Believe it or not, I'm actually glad I shaved my head all those years, because the bald cap is a bitch!" he laughed. "It took like two-and-a-half hours to get on, and it is not the most comfortable thing."

Smallville star Cassidy Freeman recently revealed that she will share a "beautiful scene" with Rosenbaum in the series finale.